Weaving with tape-like warps and wefts is of relatively recent origin. The obtaining state of the art in the field is represented by U.S. Pat. No. 6,450,208 and WO2006/075961. The specification disclosed in WO02/066721 is a conventional method of weaving in the field. The document WO2006/075961, by the same applicant, discloses a method for feeding tape-like warps in specified lengths for the shedding and fabric taking-up operations. In this method the tape-like warps are clamped and the required length drawn out from its supply spools by a suitable working arrangement described therein. This system is functionally accurate in feeding the required lengths of most types of tape-like warps but presents some drawbacks, in particular when processing certain materials.
A first drawback concerns the system's inability to draw out the warp tapes in equal lengths due to slippage in its clamping action. For example, this is a problem when tapes of very thin, flimsy and low-friction materials are to be processed. The warp tape slippage problem gets amplified especially when the diameter of the warp supply spools (or their weights) are unequal, which practically is the normal case as it is impossible to have all warp spools of either equal diameter or weight, particularly more so when the tapes are of either flimsy or delicate or special types. Furthermore, if tapes of thin, flimsy and low-friction materials are to be processed together with tapes of different materials that exhibit somewhat different physical features in relative comparison, the tape slippage problem gets even more serious and difficulties in achieving satisfactory weaving are encountered.
Of course such a feeding system could be improved by making the clamping action stronger and through use of suitable constructional materials. However, by doing so another problem crops up. The tape-like warps get indented and sometimes even deformed and damaged with broken fibers. Consequently, the quality of the resulting tape-woven material suffers.
A further drawback with the said system arises from the use of certain special tapes, e.g. tacky pre-preg tapes. Its clamping components tend to collect the tacky material from such tapes when they are used as warps in the weaving process. As a result, the tacky tape-like warps adhere to the clamps causing frequent process stops for cleaning them up resulting in associated production loss in addition to adversely affecting the quality of the woven material.
The arrangement disclosed in WO02/066721 follows a conventional approach wherein warps are drawn from a single beam source and this warp is controlled by a combination of seven rollers (pressure rollers, guide roller, floating roller and compensating rollers), all of which work in conjunction with each other before warp reaches the shedding device, to regulate warp length changes during shed opening and shed closing. This arrangement is disadvantageous at least for the following reasons: (a) The actions of all these seven rollers unduly increase the frictional forces in the warp tapes and cause tension variations in them as (i) the warp tapes have to be necessarily constantly pressed or clamped by pressure rollers, (ii) the warp tapes have to be necessarily bent around two guide and one floating rollers, (iii) the warp tapes have to be necessarily intermittently pressed by pressure rollers; (b) When processing certain tapes, such as pre-preg, stiff and brittle types of tapes, their getting pressed and bent by these rollers will also cause undesirable fiber breakage; and (c) when processing tacky type of tapes, they will tend to adhere/stick at many points making weaving nearly impossible. Obviously the arrangement according to WO02/066721 is limited in its usefulness.